The invention relates in general to a device for separating from each other materials having different melting points and capable of being plasticized in an extruder, which is particularly suitable for regenerating waste of plastics coated with a metal foil.
In the industry of consumer goods, plastics sheets coated or sealed with metal, particularly aluminum foils are employed at a rapidly growing rate. For reasons of economy, importance is increasingly attached to the regeneration of the considerable waste produced in this connection, primarily in the form of great shaped stampings.
With waste from aluminum coated plastic sheets, which occurs in large quantities, to be able to re-use the plastic, the aluminum is separated from the plastic by means of extruders equipped with metal screens. The material to be regenerated is plasticized in the extruder and pressed through a screening provided at the outlet thereof. The non-plasticized portions are caught in the screen meshes, while the plasticized material passes therethrough. In the prior art separators, however, the apertures of the screen become very soon clogged by the trapped metal, so that the screen must repeatedly be exchanged.
For this purpose, sliding frames are provided in which these screens are inserted to be introduced into the discharge channel of the extruder, however, in the regeneration of aluminum coated sheet waste, for example, the screens clog already after about 30 seconds. Therefor, they must permanently and recurrently exchange to prevent their destruction. This is not only very expensive but also very disturbing in the production, since no continuous operation is possible.